[PATCH] D31345: [XRay] [compiler-rt] Unwriting FDR mode buffers when functions are short.

Keith via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon Mar 27 01:08:03 PDT 2017


kpw updated this revision to Diff 93102.
kpw added a comment.

Changed handling of Tail call records, which I've exercised by modifying the trampoline
assembly to emit them.

Now the threshold is computed for a new buffer based on the cpu frequency and tail calls
calling into instrumented functions can be unwritten. The topmost tail exit can be replaced
with a normal exit record that records the time that the child returns multiple levels up the
stack. I think I may revert this logic because it seems better to potentially lose track of
a short amount of time in analysis of when the tail calling function is finished than perhaps
incorrectly link the tail call to information from the wrong function if its child is
uninstrumented.


https://reviews.llvm.org/D31345

Files:
  lib/xray/xray_fdr_logging_impl.h

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